Yosemite National Park
National Park Service
P.O. Box 577
Yosemite National Park, CA 95389
Both the Lukens and County Line fires have moved into patrol and mop up status. This short article helps define what that term means.
Mop up is a term used to describe extinguishing or removing burning material near control lines to make sure the fire doesn't continue to spread outside of an established containment line. It includes breaking apart smoldering debris, felling snags, ensuring hot spots holding heat are cooled or extinguished, and moving burned debris if there is a risk it could roll downhill and ignite previously unburned vegetation. The amount of area that is mopped up depends on terrain, vegetation type, and proximity to structures or other values at risk.
Firefighters mop up along the fire perimeter to ensure the fire line is cooled down enough that it will not re-ignite, even during high wind events.
When you properly extinguish your campfire by pouring water on the fire to drown all embers, thoroughly stirring in the water, adding more water (or sand), and feeling with your hand for any emanating heat, you are essentially "mopping up."